Refrigerating apparatus



Sept. 21, 1937. A. o. GROOMS REFRIGERATING APPARATUS 2 Sheets-Sheet 1Filed June 30, 1934 Se t. 21, 1937. A. o. GROOMS I REFRIGERATINGAPPARATUS Filed June 30, 1934 2 Sheets-Sheet 2 provide a simple. practiPatented Sept. 21, 1937 S PATENT OFFICE REFRIGERATING APPARATUS AlbertOakley Grooms,

General Motors Corporation,

corporation of Delaw Kpplication June 30,

11 Claims."

ditions both for normal operation and for de- I frosting, changeaccording to the external or room temperature. For example, when theroom temperature is relatively low, it is desirable to have a higherevaporator temperature for normal operation, but for defrosting undersuch conditions. it is desirable to have a lower evaporatordefrosting-temperature. Heretofore, no simple practical automatic meanshas been provided for attaining the desirable condition.

It is, therefore. an object of my invention to al, inexpensive meansoccupying little or no additional space for compensating therefrigerating apparatus and particularly the control means thereof forchanges in the environment or room temperature;

It is a more specific object of my invention to provide a simple bimetaimeans to compensate the control means for changes in external tem--perature for providing higher evaporating temperatures when theroomtemperature is relatively low'and lower evaporating temperatureswhen the room temperature is relatively high.

It is also a more specific object of my invention to providebimetal-means for compensating the control means for ture to providelower evaporator defrosting temperatures when the room temperature isrelatively, low and higher evaporator defrosting temperatures when theroom temperature is relatively high.

invention will be apparent from the following description, referencebeing had to the accompanying drawings, wherein a preferred form of thepresent invention is clearly shown.

In the drawings:

Fig. l is a sectional view of a domestic refrigerator partlydiagrammatic embodying myinventon:

Fig. 2 is a sectional view of shown in Fig. 1;

Fig. 3 is a sectional control means; and

Fig. 4 is a sectional view of another modified form of control meansembodying my invention.

Referring to the drawings, and more particularly to Fig. l, eratorcabinet iii having a food compartment 2! containing a refrigerantevaporating means 22 for cooling the food compartment 2! and also forthe control means view of a modified form of changes in externaltemperaher objects and advantages of the present there is shown aninsulated refrig- Dayton. Ohio, assignor to Dayton, Ohio, a

1934, Serial No. 733,285

freezing comestibles in the ice trays with which it is provided. Theevaporator 22 is supplied with liquid refrigerant by a refrigerantliquefying apparatus 23 including a compressor 24 for compressing therefrigerant and for forwarding the compressed refrigerant to a condenser25 where the compressed refrigerant is liquefied and collected in areceiver 26. From the receiver 26, the liquid refrigerant is forwardedthrough a liquid conduit 21 to an expansion or other suitabletype ofcontrol valve 28. This valve 28 controls the supply of liquidrefrigerant into the evaporator 22. The evaporator 22 evaporates theliquid refrigerant which is returned to the compressor through thereturn conduit 29.

The compressor 24 is driven by an electric motor 30 which is suppliedwith electric energy through an electric circuit 3|. Within the electriccircuit 3! and in series with the electric motor 30 is a control means32 which is operated by the thermostatic bulb 33 located in heatexchange relation with one of the walls of the cooling unit 22. Thecontrol means 32 is connected to the thermostatic bulb 83 by the tubing34. The control means is located outside of the food compartment 34beneath the ornamental top cover 35 r thecabinet which is provided withan opening 35 t the rear thereof for permitting the external air tocontact with the control means. Referring now more particularly to Fig.2 for a more detailed description of the control means, there is shown abellows 3B which is connected to the thermostatic bulb 38 by the tubing34. The bellows in turn is connected to operate a lever 89 pivoted to awall of the control means upon the pivot pin 8h The lever 39 isconnected by a link is provided with a set of switch contacts 53 whichcooperate with a set of stationary switch contacts' it for opening andclosing the electric motor circuit 3! in order to control the operationof the refrigerating apparatus. The operation of the control means iscontrolled by a tension coil spring 55 which is provided with a manualadlusting means $3 for regulating the temperature at which the contacts63 and M are opened and closed.

with such an arrangement, it will be understood that the temperature ofthe evaporating means will be maintained between given temperaturelimits for any particular setting of the adjusting means 66. Thus, ifthe external or environment temperature becomes warm, more heat willflow through the insulated walls of the cabinet into the foodcompartment 2!. If the M to a snap acting mechanism 62 which Itemperature of the food compartment becomes lower the evaporatortemperature. It is also true that when the room temperature is lowered,the

lower than necessary for proper food preservation because less heatenters the food compartment and this smaller amount of heat can beabsorbed by the evaporator or cooling unit at a lower temperaturedifferential between the temperature of the food compartment air and theevaporator surfaces because the rate of heat supply is less. Thus, inorder to maintain the same food compartment temperature under theseconditions, it is necessary that the evaporator temperature limits beincreased.

In order to lower the evaporator temperature automatically when theexternal or room temperature is warm and to increase the evaporatortemperature when the room temperature is low, I provide a bimetal meanshaving an upper strip 5| of iron or some other suitable material, and alower strip of brass 52 which is riveted at one end by the rivets 53 tothe lever 39 and which is connected at its opposite end to the link Mwhich connects to the snap acting mechanism 42. The control means issurrounded by air of room temperature and has the apertures 68 in thehousing or walls of the control means so that when the room or externalair temperature is higher, this temperature will eifect the bimetalstrip 50 and cause it to curl upwardly. This will cause the switchcontacts 43 and 44 to be opened and closed at lower evaporatortemperatures in order to maintain the evaporating means at a lowertemperature. When the room temperature becomes colder, the bimetal strip50 will curl downwardly and thus require higher temperatures in the bulb33 and a greater expansion of the bellows 38 in order to move thecontacts 43 and 44 to closed position. This will cause the evaporator tobe maintained between higher temperature limits when the roomtemperature is lower.

In my control means, I have also provided a periodic automaticdefrosting means for periodically increasing the temperature of theevaporat ing means to cause any frost to melt from its surfaces. This isprovided by a ratchet wheel which is mounted upon the end of the switchlever 39 and which is rotated a step at'a time by the stationaryresilient pawl 56. The switch lever is also provided with a springpressed pawl 51 for controlling the direction of rotation of the ratchetwheel 55. The ratchet wheel 55 is provided with a projection 50 which,once every revolution, engages a resistance device which resists themovement of the switch mechanism toward the closed circuit position soas to cause a higher evaporating temperature before the switch contactsmay be moved to closed positions.

It has been found that defrosting may be accomplished at a lowertemperature when the room temperature is lower because the evaporatorwarms up more slowly and more uniformly under such conditions. In orderto take advantage of this, I incorporate a bimetal comp ng means in myresistance device responsive to external or room temperatures whichreduces the amount of additional resistance provided by the defrostingmeans when the room temperature is lowered. This bimetal means takes theform of a bimetal strip having an upper strip SI of brass and a lowerstrip 62 of iron which is pivoted upon the pivot pin 63 and yieldinglyheld against a fixed stop 64 by the compression type coil spring 65which is provided with an adjusting screw 69 for varying its tension.The opposite end of the bimetal strip 60 is-provided with an adjustingscrew 66 which engages the projection 58 for providing the additionalresistance for defrosting and which may be adjusted so as to vary theadditional resistance provided and thereby to vary the defrostingtemperatures.

Once every revolution of the ratchet wheel 5|, the projection comes upand engages the lower end of the adjusting screw 56. Further upwardmovement of the switch lever 39 is resisted by the bimetal strip 00 andthe tension spring 65. When the external or room temperature is lowered,the bimetal strip 00 will curl upwardly, thus moving the adjusting screw56 upwardly slightly and reducing the resistance provided by thedefrosting mechanism. This will require a lesser force and a lowertemperature in order to move the switch contacts 43 and 44 to closedcircuit position. In this way, a lower defrosting temperature isprovided when the external temperature is lowered.

In Fig. 3, I have shown a modified form of control means in which thebimetal compensating means is made adjustable. In this form, generallydesignated by the reference character I03, is the bellows I38, which isconnected by the tubing I 34 to a thermostatic bulb which is mountedupon and in heat exchange relation with the evaporator within the foodcompartment. The bellows I38 operates the lever I39 under the control ofa tension coil spring I45 which is provided with an adjusting screw I46.The free end of, the lever I39 is connected to a snap acting toggle typeof switch contact mechanism I42 for opening and closing the switchcontacts I43 and I44. The housing or walls of the control means areprovided with apertures I68 for permitting the circulation of externalor room air through the control means.

In order to compensate the switch means and the temperature limits ofthe evaporator for changes in the external or room temperature, Iprovide a bimetal strip I50 which is fastened at one end by the rivetsI53 to a block fixed to the housing or walls of the control means. Thisbimetal strip has an upper strip I52 of iron and.

a lower strip I5I of brass. An a justing screw I 55 extends through thelever I 9 and contacts and imposes a bending movement on the bimetalstrip I50. By moving this adjusting screw I55 upwardly or downwardly,the tension exerted by the bimetal strip I50 upon the lever I39 may beadjusted. When the external or room temperature becomes lower, thebimetal strip I50 will tend to curl downwardly and increase theresistance to the expansion of the bellows I38 and thus control theoperation of the compressor of the refrigerating system so as tomaintain a higher temperature in the evaporator. When the externaltemperature becomes warmer, the bimetal strip I50 will tend to curlupwardly thus reducing the tension imposed upon the lever I39 and makingit more easy for the bellows I38 to expand and move the switch contactsto closed circuit position to cause operation of the motor com- Thus, inthis form. the switch pressor unit. means is compensated by anadjustable bimetal resistance means.

In Fig. 4, I have shown another modification embodying a double toggleswitch mechanism, the arms of which are formed of bimetal strips. Inthis form, generally designated by the reference character 204, there isprovided a metal bellows 238 connected by the tubing 234 toathermostatic bulb which is mounted upon and in heat exchange relationwith the cooling unit or evaporator of the refrigerating system. Thebellows 238 operate a primary lever 239 under the control of a tensioncoil spring 245, the tension of which may be adjusted-by an adjustingscrew 246. The primary lever 239 is provided with an insulating block210 which is provided with notches to receive the knife edges at one endof a secondary lever ZH which has its opposite or free end connected bya tension coil spring 212 to a post 2113 formed on a bimetal arm orstrip 21% of the bell crank contact lever 215. This bell crank contactlever 275 is pivoted upon the pin 276 to an insulating portion 21'!forming a part of the wall of the housing of the control means 204. Thisbell crank lever also has stop portions 218 and 219 which limit themovement of the free end of the secondary lever 2H.

The bell crank lever N5 is provided with, a second bimetal arm or stripEddwhich carries a switch contact 2% at its lower end which cooperateswith and is adapted to engage a stationary contact 282 which is mountedupon a second insulating portion 288 forming part of the wall of thehousing of the control means 2%. 1 The housing of the control means 266is provided with apertures Zed which provide for a circulation ofexternal air from the room into heat exchange relation with the bimetalstrips or arms 2'86 and 288. The bimetal strip or am 21 3 has an upperstrip Edd of brass and a lower strip 286 of iron or other suitablematerial, while the bimetal arm or strip Md-has a strip 2% of iron and astrip ml of brass. It should be noted that in this arrangement, the twocloser strips in the arms are of iron while the strips furthest away areof brass. This causes the arms to move closer together when the externaltemperature is warm, thereby reducing or lowering the cut-outtemperature which controls the stopping of the refrigerating apparatus,but without effecting the cut-in temperature which controls the startingof the re frigerating apparatus and which is adjusted by the stop screw2% which serves as the difierential adjustment.

When the external or room temperature is colder, the bimetal arms tendto curl away from each other and thus to raise the cut-out temperatureor temperature at which the reirigerah.

ing apparatus is stopped. The changing of the cut-in and cut-outtemperatures by the bimetal arms and the differential adjusting screw290 is accomplished by varying the angularity of the bell crank leverElli at the time at which the con tacts are moved to open or closedposition. This changing of the angularity, changes the angularity ofthesecondary lever 218 with respect to the primary lever its at thesetripping points and thereby varies the temperatures at which the openingand closing occurs. Thus, in this form, the bimetal compensating meansacts merely to vary the cut-out point or the stopping ture of therefrigerating apparatus.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred temperaform, it is to be understood that otherforms might be adopted, all/coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. Refrigerating apparatus-including an insulated cabinet having acompartment to be cooled, a cooling means inheat exchange relation tosaid compartment to compartment, compressing and means for supplyingmedium to said cooling means, pressure operated means dependent upon thetemperature of the cooling means for controlling said compressing means,and bimetal means thermally responsive to temperatures outside of saidcompartment for applying a resilient force for the operation of saidcontrolling means.

2. Refrigerating apparatus including an insulated cabinet having acompartment to be cooled, a cooling means in heat exchange relation withsaid compartment to be cooled for cooling said compartment, compressingand. condensing means for supplying cooling medium to said coolingmeans, means dependent upon the temperature of the cooling means forcontrolling said compressing means to normally maintain said coolingmeans at freezing temperatures, auxiliary means adecting the control ofthe compressing means for temporarily providing temperatures of thecooling means above freezing, and bimetal means responsive totemperatures outside of said compartment for regulating the temperaturesprovided by the auxiliary means.

, 3. Refrigerating apparatus including an insulated cabinet having acompartment to be cooled, a cooling means in heat exchange relation withsaid compartment to be cooled for cooling said compartment, compressingand con densing means for supplying cooling medium to said coolingmeans, means,dependent upon the temperature of the cooling means forcontrolling said compressing means said cooli means at freezingtemperatures, auxiliary means affecting the control of the compressingmeans for porarily providing temperatures of the cooling means-abovefreezing and thereafter resng normal temperature control of the coolingmeans, and means responsive to temperatures pertinent for regulating thetemperatures provided by the auxiliary means without aifecting thenormal control cooling unit.

4. Refrigerating apparatus including an insulated cabinet having acompartment to be cooled, a cooling means in heat exchange relation withsaid compartment to be cooled for cooling said compartment, compressingand condensing means for supplying cooling medium to said cooling means,means dependent of the cooling means for controlling said compressingmeans to normally maintain said cooling means at freezing means forperiodically affecting the control of the compressing means forproviding temperatures'oi' the cooling means above freezing andthereafter resuming the normal temperature control of the cooling means,and means responsive to the temperatures outside of said compartment forregulating the temperatures provided by the periodic means.

5. Refrigerating apparatus including anin sulated cabinet having acompartment to be cooled, 'a cooling means in heat exchange relation tosaid compartment to be cooled for cooling said compartment, compressingand condensto normally maintain outside of said com= upon thetemperature teratures, periodic be cooled for cooling said condensing asJ control casing containing ing means for supplying cooling medium tosaid cooling means, said compressing means including an electric motorand an electric circuit for supplying electric energy thereto, a set ofswitch contacts in series with said electric circuit for controlling thesupply of electric energy, pressure means dependent upon the temperatureof the cooling means, and bimetal means connecting the pressure meansand the switch contacts for opening and closing the switch contacts.

6. Refrigerating apparatus including a cooling unit for cooling a mediumand a circulating unit for circulating refrigerating medium through saidcooling unit, a control means including a control casing containingpressure operated means dependent upon the temperature of the coolingunit for controlling the circulating unit, said casing also containingbimetal means thermally independent of said dependent means responsiveto temperatures within the casing for applying a yielding force to thecontrol provided by said dependent means.

7. Refrigerating apparatus including a cooling unit for cooling a mediumand a circulating unit for circulating refrigerating medium through saidcooling unit, a control means including a control casing containingpressure operated means de-.

pendent upon the temperature of the cooling unit for controlling thecirculating unit, said casing being mounted within a medium surroundingand in contact with the medium surrounding one of said units of therefrigerating apparatus, said casing being provided with ventilatingapertures, said casing also containing bimetal means for applying ayielding force to the control pro vided by said dependent means.

8. Refrigerating apparatus including a cooling unit for cooling a mediumand a circulating unit 'for circulating refrigerating medium throughsaid cooling unit, a control means including a pressure operated meansdependent upon the temperature of' the cooling unit for controlling thecirculating unit,

said casing also containing bimetal means in the form of a cantileveroperably connected to said dependent means for applying a yielding forceto the control provided by said dependent means.

9. Refrigerating apparatus including a cooling I unit for cooling 9.medium and a circulating unit for circulating refrigerating mediumthrough said cooling unit, a control means including a control casingcontaining means dependent upon the temperature of the cooling unit forcontrolling the circulating unit for normally maintaining thetemperature of the cooling unit within predetermined limits, auxiliarymeans for temporarily disrupting said temperature limits, and meansresponsive to temperatures within said casing for modifying the effectof said auxiliary means without affecting the normal control of thetemperature of the cooling unit.

10. Refrigerating apparatus including a cooling unit for cooling amedium and a circulating unit for circulating refrigerating mediumthrough said cooling unit, a control means including a control casingcontaining means dependent upon the temperature of the cooling unit forcontrolling the circulating unit for normally maintaining thetemperature of the cooling unit within predetermined limits, auxiliarymeans for periodically disrupting said temperature limits, and meansresponsive to environment temperatures of one of said units of therefrigerating apparatus for modifying the effect of said auxiliarymeans.

11. Refrigerating apparatus including a cooling unit for cooling amedium and a circulating unit for circulating refrigerating mediumthrough said cooling unit, a control means including a control casingcontaining means dependent upon the temperature of the, cooling unitfor-controlling the circulating unit for normally maintaining thetemperature of the cooling unit. within predetermined limits, auxiliarymeans for temporarily disrupting said temperature limits, and bimetalmeans responsive to temperatures within said casing for modifying theefiect of said auxiliary means.

' ALBERT OAKLEY GROOMS.

